CHAPTER 7
LESSON 2
The Periodic Table
Metals
Key Concepts
What do you think? Read the two statements below and decide
whether you agree or disagree with them. Place an A in the Before column
if you agree with the statement or a D if you disagree. After you’ve read
this lesson, reread the statements to see if you have changed your mind.
Before
Statement
• What elements are metals?
• What are the properties of
metals?
After
3. Fewer than half of the elements are metals.
4. Metals are usually good conductors of
electricity.
What is a metal?
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Metals are some of the most useful elements. Forks,
knives, copper wire, aluminum foil, gold jewelry, and many
other things are made of metal.
Most of the elements on the periodic table are metals.
Except for hydrogen, all of the elements in groups 1–12 on
the periodic table are metals. Some of the elements in groups
13–15 are metals also. To be a metal, an element must have
certain properties.
Physical Properties of Metals
Recall that physical properties are characteristics used to
describe or identify something without changing its makeup.
All metals share certain physical properties. A metal is an
element that is generally shiny. It is easily pulled into wires or hammered
into thin sheets. A metal is a good conductor of electricity and thermal
energy. Gold exhibits the properties of metal.
Underline Main Ideas As
you read, underline the main
ideas under each heading.
After you finish reading,
review the main ideas that
you have underlined.
Key Concept Check
1. Explain How does the
position of an element on
the periodic table allow you
to determine if the element
is a metal?
Luster and Conductivity People use gold for jewelry because
of its beautiful color and metallic luster. Luster is the ability of a
metal to reflect light. Gold is also a good conductor of thermal
energy and electricity. However, gold is too expensive to use
in normal electrical wires or metal cookware. Copper is often
used instead.
Reading Essentials
The Periodic Table
111
Make a two-tab book to
record information about the
physical and chemical
properties of metals.
The
Physical
Properties
of Metals
The
Chemical
Properties
of Metals
Ductility and Malleability Gold is the most ductile metal.
Ductility (duk TIH luh tee) is the ability of a substance to be pulled
into thin wires. A piece of gold with a mass the same as that of
a paper clip can be pulled into a wire that is more than 3 km
long.
Malleability (ma lee uh BIH luh tee) is the ability of a substance to be
hammered or rolled into sheets. Gold is so malleable that it can
be hammered into thin sheets. A pile of a million thin sheets
of gold would be only as high as a coffee mug.
Other Physical Properties of Metals Metals have other
Key Concept Check
2. Identify What are some
physical properties of
metals?
physical properties. The density, strength, boiling point, and
melting point of a metal are greater than those of other
elements. Except for mercury, all metals are solid at room
temperature. Many uses of a metal are determined by the
metal’s physical properties.
Chemical Properties of Metals
Recall that a chemical property is the ability or inability
of a substance to change into one or more new substances.
Most metals share similar physical properties. The chemical
properties of metals, however, can vary greatly. Metals in the
same group on the periodic table usually have similar chemical
properties. The likelihood that one element will react with
another is a chemical property.
Group 1: Alkali Metals
Visual Check
3. Identify What part
of the periodic table is
represented by the figure
at right?
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The Periodic Table
Because they are in the same group, alkali
metals have similar chemical properties. Alkali
metals are very reactive. Because they react
quickly with other elements, alkali metals
occur only in compounds in nature. Pure
alkali metals must be stored so that they do
not come into contact with oxygen and water
vapor in the air. Alkali metals react violently
with water. Alkali metals also have similar
physical properties. Pure alkali metals have a
silvery appearance and are soft enough to be
cut with a knife. They also have the lowest
densities of all metals. A block of pure sodium
metal could float on water because of its very
low density.
Lithium
3
Li
6.94
Sodium
11
Na
22.99
Potassium
19
K
39.10
Rubidium
37
Rb
85.47
Cesium
55
Cs
132.91
Francium
87
Fr
(223)
Reading Essentials
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The elements in group 1 are called alkali (AL kuh li)
metals. Group 1 elements are shown on the
right. They include lithium, sodium,
potassium, rubidium, cesium, and francium.
Group 2: Alkaline Earth
Metals
The elements in group 2 are called alkaline
(AL kuh lun) earth metals. Group 2 elements are
shown on the right. They include beryllium,
magnesium, calcium, strontium, barium, and
radium.
Like alkali metals, alkaline earth metals
react quickly with other elements. But they
do not react as quickly as alkali metals do.
Like alkali metals, pure alkaline earth metals
do not occur naturally. They combine with
other elements and form compounds.
The physical properties of the alkaline earth
metals are also similar to those of the alkali
metals. Alkaline earth metals are soft and silvery.
They have low densities, but their densities
are greater than those of alkali metals.
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Groups 3–12: Transition
Elements
Visual Check
Beryllium
4
Be
9.01
4. Identify Circle the
element in the figure with
the highest atomic mass.
Magnesium
12
Mg
24.31
Calcium
20
Ca
40.08
Strontium
38
Sr
87.62
Barium
56
Ba
137.33
Radium
88
Ra
(226)
Reading Check
5. Identify Which element
reacts faster with oxygen—
barium or potassium?
The elements in groups 3–12 are called transition elements. The
transition elements are in two blocks on the periodic table.
As shown below, one block is in the center of the periodic
table. The other block is the two rows at the bottom of the
periodic table.
Many colorful materials contain small amounts of
transition elements. An emerald is green because it contains
small amounts of chromium. A garnet is red because of the
iron it contains.
Transition Elements
Visual Check
6. Identify How many
periods of transition
elements are there in the
periodic table?
Reading Essentials
The Periodic Table
113
Properties of Transition Elements
7. Contrast Describe two
differences between
transition elements and
alkali metals.
All transition elements are metals. They have higher
melting points, greater strength, and higher densities than
the alkali metals and the alkaline earth metals. Transition
elements also react less quickly with oxygen. Some transition
elements can exist in nature as free elements rather than in
compounds. Free elements occur in pure form.
Uses of Transition Elements
Transition elements in the middle block of the periodic
table have many important uses. Because they are dense,
strong, and resist corrosion, transition elements such as iron
make good building materials. Copper, silver, nickel, and
gold are used to make coins. Many transition elements can
react with other elements and form many compounds.
Lanthanide and Actinide Series
Two rows of transition elements are at the bottom of the
periodic table. They are placed below the main table to keep
the table from being too wide. Elements in the first row are
called the lanthanide series, and elements in the second row
are called the actinide series. Some elements from both series
have valuable properties. Lanthanide series elements are
used to make strong magnets. Plutonium, an actinide series
element, is used as a fuel in some nuclear reactors.
Patterns in Properties of Metals
Visual Check
Metallic properties increase
Metallic properties
increase
8. Locate Where on the
periodic table would you
expect to find elements with
few or no metallic properties?
Titanium
22
Iron
26
Copper
29
Ti
Fe
Cu
47.87
55.85
63.55
9. Identify Circle the most
malleable metal: iron (FE),
copper (Cu), or titanium (Ti).
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The Periodic Table
Reading Essentials
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Reading Check
The properties of elements follow repeating patterns across
the periods of the periodic table. The figure below shows these
patterns. Potassium (K) has more luster, is the most malleable,
and conducts electricity better than all the elements in
period 4. All these properties decrease from left to right across
the period. The elements on the far right have no metallic
properties at all. There are also patterns within groups. Metallic
properties tend to increase as you move down a group.
Mini Glossary
alkali (AL kuh li) metal: an element in group 1 on the
periodic table
alkaline (AL kuh lun) earth metal: an element in group 2
on the periodic table
ductility (duk TIH luh tee): the ability of a substance to be
pulled into thin wires
luster: the ability of a metal to reflect light
malleability (ma lee uh BIH luh tee): the ability of a
substance to be hammered or rolled into sheets
metal: an element that is generally shiny, is easily pulled into
wires or hammered into thin sheets, and is a good conductor
of electricity and thermal energy
transition element: an element in groups 3–12 on the
periodic table
1. Review the terms and their definitions in the Mini Glossary. Use three terms to tell what
properties metals tend to have.
2. Examine the section of the periodic table at right. Which
element has properties most similar to those of chromium (Cr)?
Why?
Vanadium
Chromium
23
24
25
V
Cr
Mn
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Niobium
Maganese
Molybdenum Technetium
41
42
43
Nb
Mo
Tc
3. How did underlining the main ideas help you review the material?
What do you think
Reread the statements at the beginning of the
lesson. Fill in the After column with an A if you
agree with the statement or a D if you disagree.
Did you change your mind?
Reading Essentials
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END OF
LESSON
The Periodic Table
115